U.S. patent number 6,752,595 [Application Number 10/296,306] was granted by the patent office on 2004-06-22 for propeller type windmill for power generation.
This patent grant is currently assigned to Hitachi Zosen Corporation. Invention is credited to Mitsunori Murakami.
United States Patent |
6,752,595 |
Murakami |
June 22, 2004 |
Propeller type windmill for power generation
Abstract
A plurality of wind turbine blades (3) are distributed
equiangularly within a plane perpendicular to a horizontal rotating
shaft (2) and around a hub (1) provided on the horizontal rotating
shaft (2); the blade body of each turbine blade includes
therewithin a tip auxiliary blade (6) housed to be capable of
extending toward and retracting away from a tip of the blade, and
an auxiliary blade extension-and-retraction unit (8) for protruding
the tip auxiliary blade (6) to increase the overall length of the
blade; and when an airflow comes in at a low speed, the tip
auxiliary blades (6) are protruded toward the tips to generate even
greater rotating torque, thereby increasing a power generation
output by the wind turbine.
Inventors: |
Murakami; Mitsunori (Osaka,
JP) |
Assignee: |
Hitachi Zosen Corporation
(Osaka, JP)
|
Family
ID: |
26345052 |
Appl.
No.: |
10/296,306 |
Filed: |
November 21, 2002 |
PCT
Filed: |
March 26, 2001 |
PCT No.: |
PCT/JP01/02425 |
PCT
Pub. No.: |
WO02/07744 |
PCT
Pub. Date: |
October 03, 2002 |
Current U.S.
Class: |
416/87; 416/155;
416/223R; 416/88; 416/89; 416/DIG.5 |
Current CPC
Class: |
F03D
7/0228 (20130101); F03D 1/0675 (20130101); F03D
7/0232 (20130101); F05B 2240/30 (20130101); Y02E
10/72 (20130101); F05B 2240/2023 (20130101); F05B
2240/2021 (20130101); F05B 2240/3052 (20200801); Y10S
416/05 (20130101); F05B 2240/313 (20130101) |
Current International
Class: |
F03D
7/02 (20060101); F03D 1/06 (20060101); F03D
7/00 (20060101); F03D 1/00 (20060101); F03D
007/12 () |
Field of
Search: |
;416/87,88,89,203,DIG.5,155,223R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
57032074 |
|
Feb 1982 |
|
JP |
|
59160866 |
|
Oct 1984 |
|
JP |
|
2001132615 |
|
May 2001 |
|
JP |
|
Primary Examiner: Nguyen; Ninh H.
Attorney, Agent or Firm: Hochberg; D. Peter Mellino; Sean
Vieyra; Katherine R.
Claims
What is claimed is:
1. A power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, the turbine blades each having a
blade tip, said turbine comprising: a blade body of each of said
plurality of turbine blades, wherein each body includes a tip
auxiliary blade housed in said blade body and able to extend
towards and extract away from a blade tip; an auxiliary blade
extension-and-retraction unit for protruding the tip auxiliary
blade toward the respective blade tips to increase an overall
length of the blade; and a pitch changing guide member for changing
a pitch of said tip auxiliary blade operatively connected to an
extension-and-retraction guide unit for guiding said tip auxiliary
blade to extend and retract.
2. A power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, the turbine blades each having a
blade tip, said turbine comprising: a blade body of each of said
plurality of turbine blades, wherein said body includes a tip
auxiliary blade housed in said blade body and able to extend
towards and retract away from a blade tip, and an auxiliary blade
extension-and-retraction unit for protruding the tip auxiliary
blade toward the respective blade tips to increase an overall
length of the blade; a leading edge auxiliary vane having an
airfoil-shaped cross section capable of forming, between the vane
and the blade body, a path for guiding an airflow to a rear face of
the blade body, each path being disposed at a leading edge portion
of the blade body of each of said turbine blades to be able to
extend and retract frontwardly in a rotational direction; and a
leading edge auxiliary vane extension-and-retraction unit for
protruding said leading edge auxiliary vane frontwardly in said
rotational direction and guiding the airflow from the path thus
formed to the rear face of the blade body to generate lift on the
leading edge auxiliary vane and to increase a rotating torque of
the turbine blade.
3. The power-generating propeller-style wind turbine according to
claim 2, and further comprising a pitch changing guide member for
changing a pitch of the tip auxiliary blade, and an
extension-and-retraction guide unit, said pitch changing guide
member being operatively connected to said extension-and-retraction
guide unit for guiding the tip auxiliary blade to extend and
retract.
4. A power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, the turbine blades each having a
blade tip, said turbine comprising: a blade body of each of said
plurality of turbine blades, wherein said body includes a tip
auxiliary blade housed in said blade body and able to extend
towards and retract away from a blade tip, and an auxiliary blade
extension-and-retraction unit for protruding the tip auxiliary
blade toward the respective blade tips to increase an overall
length of the blade; a leading edge auxiliary vane having an
airfoil-shaped cross section capable of forming, between the vane
and the blade body, a path for guiding an airflow to a rear face of
the blade body, each path being disposed at a leading edge portion
of the blade body of each of said turbine blades to be able to
extend frontwardly in a rotational direction; and a leading edge
auxiliary vane extension-and-retraction unit for protruding said
leading edge auxiliary vane frontwardly in said rotational
direction and guiding the airflow from the path thus formed to the
rear face of the blade body to generate lift on the leading edge
auxiliary vane and to increase a rotating torque of the turbine
blade; each of said blade bodies of each turbine blade including a
rear auxiliary vane provided at a trailing edge portion able to
extend and retract rearwardly in the rotational direction, and a
rear auxiliary vane extension-and-retraction unit for protruding
the rear auxiliary vane to extend rearwardly to increase a vane arc
length.
5. The power-generating propeller-style wind turbine according to
claim 4, and further comprising a pitch changing guide member for
changing a pitch of the tip auxiliary blade, and an
extension-and-retraction guide unit, said pitch member being
operatively connected to said extension-and-retraction guide unit
for guiding the tip auxiliary blade to extend and retract.
6. A power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, said turbine blades each having a
blade body, said turbine comprising: a leading edge auxiliary vane
having an airfoil-shaped cross section capable of forming, between
the vane and the blade body, a path for guiding an airflow to a
rear face of the blade body, each path being disposed at a leading
edge portion of the blade body of each of the turbine blades to be
able to extend and retract frontwardly in a rotational direction;
and a leading edge auxiliary vane extension-and-retraction unit for
protruding said leading edge auxiliary vane frontwardly in said
rotational direction and guiding the airflow from the path thus
formed to the rear face of the blade body to generate lift on the
leading edge auxiliary vane and increase a rotating torque of the
turbine blade.
7. The power-generating propeller-style wind turbine according to
claim 6, wherein the blade body of each turbine blade includes a
rear auxiliary vane provided at a trailing edge portion able to
extend and retract rearwardly in the rotational direction, and a
rear auxiliary vane extension-and-retraction unit for protruding
the rear auxiliary vane rearwardly to increase a vane arc
length.
8. A power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, comprising a blade body of each
turbine blade wherein each of said blade body of each turbine blade
includes a rear auxiliary vane provided at a trailing edge portion
able to extend and retract rearwardly in the rotational direction,
and a rear auxiliary vane extension-and-retraction unit for
protruding the rear auxiliary vane rearwardly to increase a vane
arc length.
Description
TECHNICAL FIELD
This invention relates to a propeller-type wind turbine used in
wind-powered electrical generation.
BACKGROUND ART
Because of its mountainous terrain, Japan, unlike Europe and
elsewhere, is not blessed with steady, strong winds suited to the
generation of electricity by wind power. In nearly all regions of
Japan, the average annual wind speed is generally under 10 m/sec,
and this is usually far below the rated output of a wind-powered
electrical generator.
The amount of electricity generated by a wind turbine is as
follows:
Generated amount W.varies..rho.(density).times.A(wind receiving
surface area).times.V(wind speed).
Therefore, the conventional approach to increasing the amount of
electricity generated by a wind turbine has been to increase the
diameter of a rotor and develop large-scale machines.
The rated wind speed corresponding to the rated output of such
large-scale machines is generally quite high (at least 10 m/sec),
and it is rare to find an area where such high wind speeds are
consistently in effect under ordinary weather conditions (that is,
other than during typhoons and other storms), and at present such
machinery operates at an output far below its rated output under
normal wind conditions. Thus, when a large-scale machine is
installed, the improvement in performance at low speed is not
commensurate with the higher installation costs entailed by the
larger structures (such as generators) required. Furthermore, a
large wind receiving surface area makes it more difficult to cope
with storm winds, so there is a higher level of danger as well.
It is therefore an object of the present invention to provide a
power-generating propeller-style wind turbine with which power
generation performance can be improved even in a low speed
range.
DISCLOSURE OF THE INVENTION
One embodiment of the present invention is a power-generating
propeller-style wind turbine provided with a plurality of turbine
blades distributed equiangularly within a plane perpendicular to a
horizontal rotating shaft and around a hub provided on the rotating
shaft, characterized in that a blade body of each turbine blade
includes therewithin a tip auxiliary blade housed to be capable of
extending toward and retracting away from a blade tip, and an
auxiliary blade extension-and-retraction unit for protruding the
tip auxiliary blade toward the blade tip so as to increase an
overall length of the blade.
With this structure, when wind speed is low, the tip auxiliary
blade extension-and-retraction unit protrudes the tip auxiliary
blades and elongates the overall length of the wind turbine blades,
which increases lift of the vanes, raises rotating torque, and
increases an amount of power generated. If the wind speed is so
high that it exceeds a rated output (such as during a storm), the
tip auxiliary blades can be retracted and stowed inside the blade
bodies, which reduces drag of the turbine blades so that the
structure is not subjected to excess load and damage can be
prevented.
Another embodiment of the present invention is directed to a
power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, characterized in that a blade body
of each turbine blade includes therewithin a tip auxiliary blade
housed in the blade body able to extend towards and retract away
from a blade tip, and an auxiliary blade extension-and-retraction
unit for protruding the tip auxiliary blade toward the blade tip so
as to increase an overall length of the blade, a leading edge
auxiliary vane having an airfoil-shaped cross section capable of
forming, between the vane and the blade body, a path for guiding an
airflow to a rear face of the blade body, which is disposed at a
leading edge portion of the blade body of each turbine blade so as
to be capable of extending and retracting frontward in a rotational
direction and a leading edge auxiliary vane
extension-and-retraction unit for protruding the leading edge
auxiliary vane frontwardly in the rotational direction and guiding
the airflow from the formed path thus formed to the rear face of
the blade body, thereby generating lift on the leading edge
auxiliary vane and increasing a rotating torque of the turbine
blade.
With this structure, lift will be generated at the tip auxiliary
blades and the leading edge auxiliary vanes and the rotating torque
will be further increased even though the incoming airflow is
moving more slowly because of the tip auxiliary blades and the
leading edge auxiliary vanes, thereby expanding the range of low
wind speeds at which power generation is feasible.
Yet another embodiment of the present invention is a
power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, characterized in that a blade body
of each turbine blade includes therewithin a tip auxiliary blade
housed to be capable of extending toward and retracting away from a
blade tip, and an auxiliary blade extension-and-retraction unit for
protruding the tip auxiliary blade toward the blade tip so as to
increase an overall length of the blade; a leading edge auxiliary
vane having an airfoil-shaped cross section capable of forming,
between the vane and the blade body, a path for guiding an airflow
to a rear face of the blade body which is disposed at a leading
edge portion of the blade body of each turbine blade so as to be
capable of extending frontwardly in a rotational direction; a
leading edge auxiliary vane extension-and-retraction unit is
provided for protruding the leading edge auxiliary vanes frontward
in the rotation direction and guiding the airflow from the path
thus formed to the rear face of the blade body, so as to generate
lift on the leading edge auxiliary vane and to increase a rotating
torque of the turbine blade; and wherein the blade body of each
turbine blade includes a rear auxiliary vane provided at a trailing
edge portion and being capable of extending and retracting
rearwardly in the rotational direction, and a rear auxiliary vane
extension-and-retraction unit for protruding the rear auxiliary
vane to extend rearwardly so as to increase a vane arc length.
With this structure, because of the increase in lift produced by
the leading edge auxiliary vanes, the increase in lift produced by
the tip auxiliary blades, and the increase in lift produced by
increasing the vane arc length and/or vane camber with the leading
edge auxiliary vanes and the trailing edge auxiliary vanes, more
lift is generated at the turbine blades, the rotating torque is
heightened, and the amount of electricity can be increased even
with a low speed airflow.
The present invention also includes a structure as set forth above
and including a pitch changing guide member for changing a pitch of
the tip auxiliary blade is provided to an extension-and-retraction
unit that guides the tip auxiliary blade to extend and retract.
With this structure, the pitch changing guide member allows the
pitch of the vane bodies to continuous with that of the tip
auxiliary blades, forming a vane of a better performance.
Still yet another embodiment of the present invention is a
power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, characterized in that a leading
edge auxiliary vane having an airfoil-shaped cross section capable
of forming, between the vane and the blade body, a path for guiding
the airflow to a rear face of the blade body which is disposed at a
leading edge portion of the blade body of each turbine blade so as
to be capable of extending and retracting frontwardly in a
rotational direction; and a leading edge auxiliary vane
extension-and-retraction unit is provided for protruding the
leading edge auxiliary vanes frontwardly in the rotational
direction and guiding the airflow to the rear face of the blade
body, thereby generating lift on the leading edge auxiliary vane
and increasing a rotating torque of the turbine blade.
With this structure, lift will be generated at the leading edge
auxiliary vanes and the rotating torque will be increased even
though the incoming airflow is moving slowly, thereby expanding the
range of low wind speeds at which power generation is feasible.
The present invention also includes a blade body of each turbine
blade includes a rear auxiliary vane provided at the trailing edge
portion and being capable of extending and retracting rearwardly in
the rotational direction, and a rear auxiliary vane
extension-and-retraction unit for protruding the rearwardly so as
to increase a vane arc length.
With this structure, because of the increase in lift produced by
the leading edge auxiliary vanes and the increase in lift produced
by increasing the vane arc length and/or vane camber with the rear
auxiliary vanes, more lift is generated at the turbine blades, the
rotating torque is heightened, and the amount of electricity can be
increased even with a low speed airflow.
Yet another embodiment of the present invention is a
power-generating propeller-style wind turbine provided with a
plurality of turbine blades distributed equiangularly within a
plane perpendicular to a horizontal rotating shaft and around a hub
provided on the rotating shaft, characterized in that the blade
body of each turbine blade includes a rear auxiliary vane provided
at a trailing edge portion and being capable of extending
rearwardly in a rotational direction, and a rear auxiliary vane
extension-and-retraction unit for protruding the rear auxiliary
vane rearwardly so as to increase a vane arc length.
With this structure, the rear auxiliary vanes increase the vane arc
length and/or the vane camber, and as a result, increase the lift
generated at the turbine blades thereby to increase the rotating
torque, so that more electricity can be generated even with a low
speed airflow.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 (a) and (b) illustrate a first embodiment of a
power-generating propeller-style wind turbine pertaining to the
present invention, with (a) being an overall front view of tip
auxiliary blades in an extended state, and (b) an overall front
view of the tip auxiliary blades in a stowed state.
FIG. 2 is an overall structural diagram of a turbine blade of the
same power-generating propeller-style wind turbine.
FIGS. 3 (a) and (b) illustrate an extension-and-retraction guide
unit of the same turbine blade, with (a) being a front view of the
tip auxiliary blade in the extended state, and (b) an overall front
view of the tip auxiliary blade in the stowed state.
FIG. 4 is a cross section along a B--B line in FIG. 3 (a).
FIG. 5 is a cross section along a C--C line in FIG. 4.
FIG. 6 is a cross section along a D--D line in FIG. 3 (a).
FIG. 7 is a cross section along an A--A line in FIG. 3 (a).
FIG. 8 is a graph showing relationship between wind speed and power
generation in the same power-generating propeller-style wind
turbine.
FIG. 9 is a structural diagram illustrating a variation example of
pitch addition means and an extension-and-retraction guide unit in
the first embodiment.
FIG. 10 is a cross section along an E--E line in FIG. 9.
FIGS. 11 (a) and (b) illustrate a second embodiment of the
power-generating propeller-style wind turbine pertaining to the
present invention, with (a) being an overall front view of leading
edge auxiliary vanes and rear auxiliary vanes in the extended
state, and (b) an overall front view of the leading edge auxiliary
vanes and rear auxiliary vanes in the stowed state.
FIG. 12 is a lateral cross section of the leading edge auxiliary
vane and the rear auxiliary vane of the same turbine blade when
stowed.
FIG. 13 is a lateral cross section of the leading edge auxiliary
vane and the rear auxiliary vane of the same turbine blade when
extended.
FIG. 14 is a partial enlarged front view of the same turbine
blade.
FIGS. 15 (a) to (c) are lateral cross sections illustrating
operations of the same turbine blade, with (a) being an operational
diagram during normal power generation, (b) an operational diagram
when the wind is calm, and (c) an operational diagram when the
leading edge auxiliary vanes are extended.
FIGS. 16 (a) and (b) illustrate a third embodiment of the
power-generating propeller-style wind turbine pertaining to the
present invention, with (a) being an overall front view of the tip
auxiliary blades, leading edge auxiliary vanes and rear auxiliary
vanes in the extended state, and (b) an overall front view of the
tip auxiliary blades, leading edge auxiliary vanes and rear
auxiliary vanes in the stowed state.
BEST MODE FOR CARRYING OUT THE INVENTION
In order to describe the present invention in further detail, a
first embodiment of the power-generating propeller-style wind
turbine will be described through reference to FIGS. 1 to 8.
As shown in FIGS. 1 to 3, this propeller-style wind turbine has a
hub 1 provided to a horizontal rotating shaft linked to a
generator. This hub 1 is provided, for example, with three turbine
blades 3 that extend radially at 120.degree. intervals. The turbine
blades 3 each comprise a blade body 4 attached to the hub 1, a main
end plate 5 attached to the tip of the blade body 4, a tip
auxiliary blade that is housed in the blade body so that it can
extend from and retract into the main end plate 5 and has a tip end
plate 7, and a tip auxiliary blade extension-and-retraction unit 8
for extending and retracting the tip auxiliary blade 6. The tip
auxiliary blade extension-and-retraction unit 8 is provided with an
extension-and-retraction guide member 9 that guides the tip
auxiliary blade 6 to extend and retract and imparts a pitch
thereof.
A continuously varying small pitch .O slashed. (not shown)
centering approximately around the blade axis O is imparted to the
tip auxiliary blade 6. The tip auxiliary blade 6 comprises a
parallel section 6a where the leading and trailing edges are
parallel at the proximal end, a tapered section 6b where the
leading and trailing edges taper together at the distal end of the
parallel section 6a, and the tip end plate 7 attached to the distal
end surface of the tapered section 6b. A slide support member 6d
extending along the blade axis O inside the blade body 4 is linked
to the parallel section 6a.
As shown in FIGS. 2 and 3, the tip auxiliary blade
extension-and-retraction unit 8 comprises an
extension-and-retraction drive motor 21 provided to the hub 1, an
extension-and-retraction threaded shaft 23 that is rotationally
driven by the extension-and-retraction drive motor 21 via a bevel
gear mechanism 22, and a female threaded member 24 which is
provided to the proximal end of the slide support member 6d and
into which the extension-and-retraction threaded shaft 23 is
fitted.
When the tip auxiliary blade 6 is extended, the turbine blade 3 has
a large pitch .O slashed. (say, about 20.degree.) at its proximal
end, and the pitch .O slashed. decreases toward the tip, with the
blade being twisted so that the pitch .O slashed. will be close to
0.degree. at the tip, and the cross sectional shape also varies
continuously. Since there is little change in the pitch .O slashed.
on the tip side of the blade body 4 where the tip auxiliary blade 6
is housed, sufficient space is ensured for allowing the tapered
section 6b, which has a small cross sectional area compared to the
rest of the tip auxiliary blade 6, to be extendably stowed, but the
parallel section 6a on the proximal end side has a larger cross
sectional area, so there is not enough room for it to be twisted
and still be able to extend and retract. Accordingly, if the
parallel section 6a is extended and retracted linearly along its
cross sectional shape, there will be a problem in that the pitch .O
slashed. is no longer continuous where the parallel section 6a
links to the blade body 4. This is dealt with in this embodiment by
moving the tapered section 6b linearly from the tip portion of the
tip auxiliary blade 6 to a midway point, and thereafter when the
parallel section 6a is extended, moving it while imparting a small
amount of rotational displacement to the parallel section 6a with
the extension-and-retraction guide member 9 of the tip auxiliary
blade extension-and-retraction unit 8. As a result, when the tip
auxiliary blade 6 has been extended all the way, the pitch .O
slashed. is continuous all along the blades 4 and 6.
Specifically, the extension-and-retraction guide member 9 comprises
a pitch changing guide member 9a that adds pitch and guides the
parallel section 6a at the tip portion inside the blade body 4, and
a slide guide member 9b that guides the above-mentioned slide
support member 6d. As shown in FIGS. 4 and 5, the pitch changing
guide member 9a is such that a pair of twist guides 11A and 11B, on
each of which is formed an arc guide surface 11a centering around
the blade axis O, with these surfaces facing each other, are
attached within the blade body 4 in order to add rotational
displacement to the tip auxiliary blade 6 so that the parallel
section 6a moves around the blade axis O. Twist members 12 are
disposed between the twist guides 11A and 11B so as to be rotatable
around the blade axis O along the arc guide surfaces 11a. Slide
recesses 12a for guiding the parallel section 6a are formed in the
twist members 12. A ball guide 13 juts out from the leading edge
part of the parallel section 6a, and a twist guide groove 14 for
guiding the ball guide 13 is formed in the twist guide 11A. As
shown in FIG. 5, the twist guide groove 14 is angled by a specific
amount .delta. in the direction in which the pitch .O slashed. is
formed so as to achieve the specified rotational displacement at
the top.
Therefore, as the tip auxiliary blade 6 extends and moves closer to
its limit of extension, the parallel section 6a is guided by the
slide recesses 12a of the twist members 12, the ball guide 13 moves
along the twist guide groove 14, and as the limit of extension is
approached, the inclination of the twist guide groove 14 causes the
tip auxiliary blade 6 to be extended along with the twist members
12 via the parallel section 6a, while twisting by the specified
rotational displacement .delta. around the blade axis O.
As shown in FIGS. 3 and 6, the slide guide member 9b is designed
such that the slide support member 6d is formed with a hollow
rectangular cross section, while a guide frame 17, which has a
rectangular cross section and is supported by the blade body 4, is
provided along the blade axis O, and the slide support member 6d is
slidably fitted over the guide frame 17 via corner members 18. The
extension-and-retraction threaded shaft 23 is supported by a
bearing 25 and has a plurality of movable joints 23a interposed on
its proximal end side, allowing it conform to the twisting of the
extension-and-retraction threaded shaft 23.
FIG. 8 is a graph of the relationship between wind speed and power
generation in a power-generating propeller-style wind turbine. For
example, the turbine blades 3 begin rotating from a cut-in line at
a wind speed of approximately 3 to 4 m/sec, and reach the specified
rotational speed within a short time. The amount of power generated
increases as a function of the rotating torque obtained at that
wind speed. Specifically, with a conventional wind turbine with a
rated output (power generation) of 600 kW, for example, as
indicated by curve a, power generation increases as a function of
wind speed, the rated output is obtained at the rated wind speed
(about 13 m/sec), and any further increase in wind speed results in
no further increase in power generation. With a conventional wind
turbine with a rated power generation (output) of 1200 kW, as
indicated by curve b, there is sharp rise in power generation as
wind speed increases, and once again the rated output is obtained
when the rated wind speed (about 13 m/sec) is reached. With the
present invention, when, for example, the rated power generation is
set to be 600 kW when the tip auxiliary blades 6 are stowed, and
the rated power generation is set to be 1200 kW when the tip
auxiliary blades 6 are extended, as indicated by curve c, since the
tip auxiliary blades 6 are extended when wind speed is low, a high
rotating torque is obtained and power generation increases just as
with a wind turbine whose rated power generation is 1200 kW. If the
rated wind speed is set to 10 m/sec on the basis of the strength of
the turbine blades 3, for example, then when the tip auxiliary
blades 6 are retracted and stowed inside the blade bodies 4, as
indicated by curve c-1, there is a drop in power generation to the
rated 600 kW, after which the rated power generation of 600 kW is
maintained. If the rated wind speed is 12 m/sec, as indicated by
curve c-2, the power generation again drops to 600 kW. Similarly,
when the rated wind speed is 13 m/sec, as indicated by curve c-3,
the output drops to 600 kW. Thus, in every case, when the wind
speed is between 6 and 13 m/sec, the amount of power generated is
higher than that of a wind turbine with a rated output of 600 kW by
the amount indicated by hatching.
If there is a powerful wind blowing faster than about 25 m/sec,
this is used as the cut-out wind speed, at which the rotation of
the turbine blades 3 is forcibly halted in order to prevent
damage.
With the above structure, the construction scale and expense can be
kept small, and a large lift and rotating torque can be obtained
and high power generating performance achieved at low wind speed by
using the tip auxiliary blades 6. At the rated wind speed, the tip
auxiliary blades 6 can be stowed so as to maintain the rated
output. This allows the wind speed at which power generation can be
increased to be set over a wider range that includes lower wind
speeds. Furthermore, because the pitch addition means 11 provided
to the extension-and-retraction guide unit 9, when the tip
auxiliary blades 6 are extended from inside the blade bodies 4, a
specific rotational displacement is imparted, allowing a continuous
pitch to be formed from the blade bodies 4 to the tip auxiliary
blades 6, so operation is more efficient.
FIGS. 9 and 10 illustrate a variation example of the auxiliary
blade extension-and-retraction unit and the pitch addition
means.
Specifically, a revolving member 34 is provided to the main end
plate 5 via a pitch changing bearing 33, and the proximal end of
the tip auxiliary blade 6 is removably fitted into a support hole
35 in the revolving member 34. A pitch changing shaft 30 extending
along the blade axis O is attached in the proximal end direction to
the tip auxiliary blade 6, and an auxiliary blade pitch changing
unit (pitch addition means) 31 for changing the pitch of the tip
auxiliary blade 6, and an auxiliary blade extension-and-retraction
unit 32 for driving the tip auxiliary blade 6 to extend and retract
are provided via the pitch changing shaft 30.
The pitch changing shaft 30 comprises a circular shaft component
30a at the distal end, and a rectangular shaft component 30c linked
via a flange 30b to the proximal end of the circular shaft
component 30a. The auxiliary blade pitch changing unit 31 comprises
a transmission gear component 31c consisting of a driven gear 31a
fitted slidably in the axial direction to the rectangular shaft
component 30c, and a drive gear 31b that meshes with the driven
gear; a low-speed gearbox 31e that drives the drive gear 31b via an
intermediate shaft 31d; and a pitch changing input component 31g
that inputs to the low-speed gearbox 31e by means of a step motor
31f, either directly or via a rack and input pinion.
The auxiliary blade extension-and-retraction unit 32 has
substantially the same structure as in the previous example, but
transmission arms 32c having an antirotation mechanism 32b
consisting of a guide member and a guide groove are provided to a
slide member 32a having a pair of upper and lower female threaded
members 28, and the circular shaft component 30a of the pitch
changing shaft 30 is linked to these transmission arms 32c so as to
be capable only of rotation. Specifically, cylinder members 32d
that fit over the circular shaft component 30a are attached to the
transmission arms 32c, and rotatable transmission bearings 32e are
fixed to the top and bottom parts of each of the cylinder members
32d on the circular shaft component 30a. As a result, an
extension-and-retraction drive force is transmitted along the blade
axis O of the transmission arms 32c to the circular shaft component
30a, which drives the extension-and-retraction of the tip auxiliary
blade 6.
According to this embodiment, the same effects as in the previous
embodiment can be obtained, and furthermore it is possible to
generate power efficiently while keeping the turbine blades 4 at a
constant rotational speed by changing the pitch .O slashed. of the
tip auxiliary blades 6 with the auxiliary blade pitch changing unit
31 via the pitch changing shaft 30 as dictated by the wind
speed.
A second embodiment of a power-generating propeller-style wind
turbine will now be described through reference to FIGS. 11 to
15.
With this propeller-style wind turbine, turbine blades 41 extend
from a hub 40 every 120.degree., a plurality of leading edge
auxiliary vanes 43 are provided to the leading edges of blade
bodies 42 so as to be extendable and retractable frontward in the
rotation direction, and rear auxiliary vanes 51 are provided to the
rear part of the blade bodies 42 so as to be extendable and
retractable rearward in the rotation direction.
As shown in FIGS. 11 to 13, each blade body 42 is provided with an
end blade 44 at its distal end, and is formed in an airfoil-shaped
cross section. Leading edge auxiliary vanes 43 that are able to
move away from the blade body 42 are provided all the way from the
leading edge of the blade body 42 to the rear face, divided into a
plurality of segments in the lengthwise direction. Leading edge
auxiliary vane extension-and-retraction units 50 that drive the of
the leading edge auxiliary vanes 43 to extend and retract frontward
are provided inside the blade body 42. These leading edge auxiliary
vanes 43 are formed with a cambered airfoil-shaped cross section,
and move away from the blade body 42 when extended frontward in the
rotation direction. This forms a path 45 for guiding the airflow
between the blade body 42 and the leading edge auxiliary vanes 43
to the rear face of the blade body 42. This path 45 streamlines the
airflow moving to the rear face of the blade body 42, so lift and
rotating torque are generated at the leading edge auxiliary vanes
43 even when the incoming airflow is low in speed.
The leading edge auxiliary vane extension-and-retraction units 50
are such that a plurality of support guide plates 46 are provided
extending toward the blade body 42 in the extension and retraction
direction from the rear surface of the leading edge auxiliary vanes
43, and are inserted into extension and retraction holes 49 in the
blade body 42. The support guide plates 46 are extendably and
retractably guided and supported by a plurality of grooved guide
rollers 47 inside the blade body 42. The output rods of a plurality
of extension-and-retraction drive units (such as hydraulic cylinder
of electric jacks) 48 disposed inside the blade body 42 are linked
to the support guide plates 46 so that the leading edge auxiliary
vanes 43 can be driven to extend and retract.
The basic principle behind the performance of the leading edge
auxiliary vanes 43 will now be described.
As shown in FIG. 15 (a), when a turbine blade 41 rotates at a
specific speed and encounters an airflow with a velocity of Vw, the
airflow comes in at a velocity of Vi in a relative angular
direction (blade attachment angle .beta.+angle of incidence
.alpha.). As a result, a drag D in the incoming direction and a
lift L in the direction perpendicular to the incoming direction are
generated, the component force of the lift L in the rotation
direction acts on the turbine blade 41 as a force Tr that generates
rotating torque, and a generator is actuated by this force Tr that
generates rotating torque, thereby generating electricity. As shown
in FIG. 15 (b), when the velocity Vw of the airflow is low, no lift
L is generated and the airflow does not contribute to power
generation.
In this case, as shown in FIG. 15 (c), when the leading edge
auxiliary vanes 43 are extended forward from the blade body 42, the
airflow Vw is guided by the leading edge auxiliary vanes 43 so that
it flows from the path 45 toward the rear face of the blade body
42, any eddy currents are smoothed out to prevent separation flow
and promote the generation of lift L at the blade body 42, a force
Tr' that generates rotating torque and lift L' at the leading edge
auxiliary vanes 43 is generated by a relative inflow velocity Vi'
toward the leading edge auxiliary vanes 43, this force Tr' acts on
the blade body 42 so that rotating torque that contributes to power
generation will be generated at the turbine blade 41 even with a
low-speed airflow Vw, and the rotating speed is accelerated,
allowing power to be generated at the specified rotating speed.
A plurality of rear auxiliary vanes 51 are arranged in the
lengthwise direction along the blade body 42. These rear auxiliary
vanes 51 are disposed so as to be capable of rearward extension
from and retraction into extension-and-retraction holes 52 in the
trailing edge of the blade body 42. Also, rear auxiliary vane
extension-and-retraction units 53 that increase the vane arc length
of the turbine blade 41 by extending the rear auxiliary vanes 51
rearward are provided inside the blade body 42.
These rear auxiliary vanes 51 each comprise a vane plate 51a
disposed slidably along the inner surface of a back plate 42a of
the blade body 42, and a reinforcing rib 51b provided to the front
side of the vane plate 51a in the extension-and-retraction
direction. The rear auxiliary vane extension-and-retraction units
53 comprise a plurality of grooved guide rollers 54 that extendably
and retractably guide the vane plates 51a via the reinforcing ribs
51b, and a plurality of extension-and-retraction drive units (such
as hydraulic cylinders or electric jacks) 55 in which the output
rods are linked to the rear auxiliary vanes 51 within the blade
body 42. The rear auxiliary vanes 51 can be extended rearward from
the extension-and-retraction holes 52 by deploying the
extension-and-retraction drive units 55.
With the above structure.sup..circleincircle., when the turbine
blade 41 rotates at a specific speed and the velocity of the
airflow coming in to the wind turbine is low, as shown in FIGS. 11
and 13, the leading edge auxiliary vanes 43 are extended rearwardly
by the leading edge auxiliary vane extension-and-retraction units
50, and the rear auxiliary vanes 51 are extended by the rear
auxiliary vane extension-and-retraction units 53.
Lift L is generated by the leading edge auxiliary vanes 43, the
component force thereof generates a force Tr' that generates
rotating torque, and this force Tr' acts on the blade body 42,
which yields a higher rotating torque. Either the vane arc length
of the turbine blade 41 is increased, or the vane camber is
increased, or the vane arc length and vane camber are both
increased, by the rear auxiliary vanes 51, thereby increasing the
force Tr that generates the rotating torque of the blade bodies 42.
The result of these effects is that even with a low-speed airflow,
the turbine blades 41 can be rotated at the specified speed and a
high torque obtained, affording an increase in the amount of power
generated.
It is also possible to extend just the leading edge auxiliary vanes
43 or the rear auxiliary vanes 51 according to the incoming
velocity of the airflow. Naturally, if the airflow velocity is
high, the leading edge auxiliary vanes 43 should be retracted into
the blade body 42, and the rear auxiliary vanes 51 should be
retracted and stowed in the blade body 42 as well. This lowers the
drag of the turbine blade 41 prevents damage that could be caused
by strong winds.
FIG. 16 illustrates a third embodiment that combines the first
embodiment with the second embodiment. The tip auxiliary blades 6,
the leading edge auxiliary vanes 43, and the rear auxiliary vanes
51 are all extendably and retractably housed within a blade body 61
of a turbine blade 60.
With this structure, the effects of the first embodiment are
combined with the effects of the second embodiment, so that even if
the airflow is slower yet, effective rotating torque can be
generated by the tip auxiliary blades 6, the leading edge auxiliary
vanes 43, and the rear auxiliary vanes 51, allowing power to be
generated.
Industrial Applicability
As discussed above, the power-generating propeller-style wind
turbine pertaining to the present invention is suited to
wind-powered electrical generation in such areas where the wind
speed is low.
The invention has been described with particular reference to cues
for playing pool. The features of the invention could also be used
for similar games such as billiards, snooker, bumper pool and the
like. What has been described above are preferred aspects of the
present invention. It is of course not possible to describe every
conceivable combination of components or methodologies for purposes
of describing the present invention, but one of ordinary skill in
the art will recognize that many further combinations and
permutations of the present invention are possible. Accordingly,
the present invention is intended to embrace all such alterations,
combinations, modifications, and variations that fall within the
spirit and scope of the appended claims.
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